The Fortifications of Quebec City are a series of defensive walls and structures built to protect the city from invasions. Constructed in the 17th and 18th centuries, they are the only remaining fortified city walls in North America. The fortifications include gates, bastions, and a citadel, showcasing military architecture from the colonial period. These walls encircle the historic district of Old Quebec, a UNESCO World Heritage site. The fortifications played a crucial role during conflicts such as the Battle of Quebec in 1759. Today, they serve as a popular tourist attraction, offering insights into the city's rich history.